The proposed study is part of a broad morphological and biochemical characterization of the byssus apparatus of Mytilis californianus. The objectives are: 1) to define the chemical nature of the various parts of the composite byssus, with emphasis on the adhesive properties of the attachment disc; 2) to delineate the biochemical and cytological processes involved in formation of the byssus. Modern methods for determining protein and glycoprotein structure will be applied to study as well as cell fractionation procedures based on knowledge of the morphological and cytological organization of the byssus-forming glands.